Bucket control mechanism for power shovels



c. P. BECKER 3,343,693

BUCKET CONTROL MECHANISM FOR POWER SHOVELS 5 Sheets-:Sheet 1 Sept. 26, 1967 Filed Dec. 23. 1965 (0/ .P ficcker INVENTOR C. P. BECKER Sept. 26, 1967 BUCKET CONTROL MECHANISM FOR POWER SHOVELS 5 Sheets-Sheet 2 Filed Dec. 23, 1965 Fig 2 Car/ P Becker INVENTOR.

JTTOfi/VE V Sept. 26, 1967 c. P. BECKER BUCKET CONTROL MECHANISM FOR POWER SHOVELS 5 Sheets-Sheet 5 Filed Dec. 23, 1965 Sept. 26, 1967 c. P. BECKER BUCKET CONTROL MECHANISM FOR POWER SHOVELS 5 Sheets-Sheet 4- Filed Dec. 23, 1965 INVENTOR.

I Cbr/ flecker Sept. 26, 1967 c. P. BECKER BUCKET CONTROL MECHANISM FOR POWER SHOVELS 5 Sheets-Sheet 5 Filed Dec. 23. 1965 C P Becker INVENTOR.

United States Patent 3,343,693 BUCKET CONTROL MECHANISM FOR POWER SHOVELS Carl P. Becker, 931 St. Andrews Drive, Sarasota, Fla. 33580 Filed Dec. 23, 1965, Ser. No. 515,955 15 Claims. (Cl. 214-138) ABSTRACT OF THE DISCLOSURE A power shovel 20 comprises a boom 22, dipper stick 23 and a bucket 24 pivoted to the dipper stick. The angle of the bucket to the dipper stick is shifted about a pivot 31 by a motor 32 so as to maintain the bucket at the most eflicient angle to the earth during a scoop movement in which the leading edge of the bucket is moved in a plane, the motor being automatically controlled by valving 66 in accordance with parallelogram type linkage 61, 74, 80, 100. The bucket is also swingable about an axis 51 by hydraulic motor means 155 operating a sleeve 137 on a helix 136 to position an axle pin 51 to which the bucket is attached for shifting the bucket about a pivot extending in the plane of swinging movement of the boom and dipper stick. In a second form of the invention a bucket 202 is attached to the dipper stick 200 by a pivot pin 220 so as to swing on an axis lying in the plane in which the boom and dipper stick swing and the bucket is positioned about this axis by two hydraulic motors 230, 231 connected to the bucket support by arms 223, the connections being through universal joints 236, 237. The motors are attached to the links 206, 225 by universal joints 232, 233.

The present invention relates to earth handling apparatus and more particularly to power shovels of the type comprising a scoop bucket attached to the distal end of a dipper stick pivotally supported on a boom.

Power shovels of a conventional type comprise a suitable revolvable platform having an upwardly and outwardly extending boom supported thereon for pivotal movement about a horizontal axis by power means. A dipper stick is pivotally attached to the outer or swinging end of the boom on a horizontal axis and extends generally downwardly and is swung in a vertical plane by power means. The dipper stick carries a bucket or scoop at its distal end and the bucket is pivoted to the dipper stick so that it can be tilted about a horizontal axis to present different angles of attack to the ground by the leading edge of the open side of the bucket, which angle of tilt is likewise controlled by power means. The power means for the boom, dipper stick and bucket are usually hydraulic motors controlled individually by the shovel operator. When it is desired to form a finished grade along a given plane, as by drawing the bucket toward the platform with the open side of the bucket facing the platform, it is necessary to simultaneously operate the boom elevation control motor, the dipper stick motor and the bucket angle motor to move the bucket in a scooping action along the level or plane desired. This control operation is diflicult and awkward and generally results in unsatisfactory and uneven grading.

A principal object of the present invention is the provision of a power shovel of the character mentioned in which the angle of the bucket to the plane or grade to be made can be automatically controlled to remain substantially constant to the grade so that the shovel operator need only concern himself with the control of the boom and dipper stick motors, thereby providing more accurate and effective earth grading.

Another object of the invention is the provision of a new and improved power shovel of the type mentioned in 3,343,693 Patented Sept. 26, 1967 which the motor affecting the bucket angle is controlled by means comprising linkage corresponding substantially to a parallelogram, one long side of which is the dipper stick and one short side corresponds to a side of the bucket so that as the dipper stick is swung on its pivot the bucket angle motor is actuated to tilt the bucket relative to the dipper stick and maintain its angle with the dipper stick corresponding to the angle between the long and short sides of the corresponding swinging parallelogram. Preferably, means are provided for compensating the control to nullify the raising and lowering eifect of the boom on the angle of the bucket.

Another important object of the invention is the provision of a power shovel of the type referred to in which the bucket is attached to the dipper stick by means providing for rotation of the bucket not only about an axis parallel to the axis of rotation of the dipper stick relative to the boom but also about an axis lying in the plane in which the boom and dipper stick swing so that the bucket may be positioned with the earth scooping edge at an acute angle relative to the vertical plane in which the dipper stick swings and including power means to position the bucket about the last mentioned axis. In the preferred form of power shovel, means are provided for maintaining the angle of the bucket at a substantially constant angle to a predetermined grade or level as the boom and dipper stick move the bucket along such level.

Other objects and advantages of the invention will be apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings wherein:

FIG. 1 is a fragmentary side elevational view of a power shovel embodying one form of the invention;

FIG. 2 is a fragmentary, plane View of a dipper stick of the power shovel shown in FIG. 1, showing a control valve thereon;

FIG. 3 is a fragmentary sectional view taken substantially along line 33 of FIG. 2;

FIG. 4 is a fragmentary side elevational view of the boom and valve shown in FIG. 3;

FIG. 5 is a fragmentary sectional view taken substantially along line 5-5 of FIG. 6;

FIG. 6 is a fragmentary plan view in elevation showing a clamping means on the boom of the power shovel;

FIG. 7 is a diagram of a portion of the control system for the power shovel;

FIG. 8 is a side view, partly in section, taken substantially along line 88 of FIG. 6;

FIG. 9 is a side elevational view of a fragment of the power shovel shown in FIG. 1, and drawn on a larger scale;

FIG. 10 is an end elevational view of the power shovel shown in FIG. 9;

FIG. 11 is a sectional view taken substantially on lines 1111 of FIGS. 9, 12, and 13;

FIGS. 12 and 13 are sectional views taken along lines 12, 1312, 13 of FIG. 11 and showing certain parts of the mechanisms in different positions;

FIG. 14 is a fragmentary side view in elevation of a power shovel embodying a second form of the invention;

FIG. 15 is a front elevational view of the power shovel shown in FIG. 14; and

FIG. 16 is a fragmentary view on a larger scale of a portion of the apparatus shown in FIG. 15.

Referring to FIGS. 1 through 13 of the drawings, a power shovel 20 is shown embodying one form of the invention. The shovel is of the type known as a backhoe and comprises in general, a suitable platform 21, a boom 22, pivoted to the platform, a dipper stick 23 and a bucket or scoop 24.

The platform 21 is supported on a suitable vehicle, not shown, and is rotatable about a vertical axis by suitable power means under control of the operator. The boom 22 is pivoted to the platform at 25 so as to swing in a vertical plane, assuming the platform 21 to be horizontal, about the horizontal axis of its pivot and is shifted on its pivot by a hydraulic motor 26 which is capable of locking the boom in any given position.

The dipper stick 23 is pivoted to the boom 22 at 27 and swings in the same vertical plane as does the boom, and is actuated about its pivot by a hydraulic motor 3%. The bucket 24 is pivotally attached to the distal end of the dipper stick at 31 and is movable about its pivotal axis by a hydraulic motor 32.

The pivoting structures for the platform, boom and dipper stick and the control system for the rotation of platform 21 and the actuation of motors 26, 39 and 32 are conventional and for sake of clarity are not shown, except for that portion of the control system required to understand the invention.

The bucket 24 has an open side 33 with teeth along the lower leading edge 34 which edge penetrates the earth so that earth is scooped or crowded into the bucket as the dipper stick swings the bucket towards the platform.

The bucket 24 per se is of conventional construction including a side wall 35 which initially receives the earth scooped into the bucket, and which wall merges with curved end wall 36 which is likewise merged with a top wall 37. The sides of the bucket are closed by walls 4s, 41 which are suitably joined with the side edges of walls 35, 36, 37.

The top wall 37 has two parallel support flanges 42, 43 having openings through which support pins 44, 4-5 extend and which are in turn supported on two pairs of lugs 46, 47 depending from a U-bracket 59. The outer ends of the bracket 50 are attached to opposite ends, respectively, of a rocker shaft 51 which is angularly positionable by power operate-d positioning means 52, described more fully hereinafter, so-that the bucket can be selectively positioned about an axis extending longitudinally in the plane in which the dipper stick swings, as is explained more fully hereinafter.

The positioning means 52, includes a housing 53 having two pairs of support lugs 54, 55, the lugs 54 being pivotally connected to the dipper stick by the pin 31 extending through the dipper stick and having its ends supported in openings through the lugs.

The lugs 55 are pivotally connected to a pin 56 which is supported in the end of a link 57, formed of two parallel bars, the upper ends of which are pivoted by a pin 69 to the outer end of a link 61, also comprised of two parallel bars pivoted to either side of the dipper stick on a pin 62.

The pin 60 is carried in the end of a piston rod 63 of the hydraulic motor 32, which includes a double acting piston operating in a cylinder 64, the upper end of which is pivotally anchored to the dipper stick at 65. The pivotal connections and the hydraulic motor 32 are not shown in detail as such devices and structures are well known in the art.

To maintain the angle of the side 35 of the bucket with horizontal so that earth may be crowded into and retained in the bucket as the boom and dipper stick are operated to scoop earth along a given plane, and to more easily control the elevation at which the bucket engages the earth, the motor 32 is operated to shift the bucket about its pivot 31, all of which is well understood in the art. In accordance with my invention, the motor 32 is automatically controlled to cause the angle of the side 35 of the bucket with a given level to be maintained sub-- stantially constant as the dipper stick and the boom are moved to scoop earth. In FIG. 1, a shovel embodying the invention is shown grading on a level L and the scooping action is illustrated by full and dotted lines.

The automatic control of the movement of the bucket 24 about its pivot 31 referred to is effected by a control valve 66 which is slidingly supported on a guide bar 67,

T-shaped in transverse section, attached to the dipper stick. The valve 66 is attached to a slide member 70 which has groove forming flanges 71, 72 L-shape in transverse section and extend along opposite sides of the memher to provide guides for receiving the outer ends of the cross flange of the guide bar. Thus, the slide member 70 is held to the guide bar and in sliding relation therewith. The valve 66, which is a conventional spool type four-way valve, has its housing bolted to the slide 70 and moves therewith. The slide 70 has a pin 73 to which one end of a link rod 74 is pivotally attached and the opposite end of the rod is attached to the link 61 by a pivot pin 75.

The valve 66 includes a spool 76 which extends from the end of the valve housing opposite the end attached to red 74 and is pivotally attached at 77 to one end of a second link rod 39. The relative movement of the spool 76 and the valve housing controls the motor 32 as is described more fully hereinafter.

The other end of the link rod 8t) is slidingly supported on the boom 22 by a guide clamp 81, which is located on an extension of the boom beyond the pivot 27 and which clamp, when released, guides the rod for longitudinal sliding movement, or when actuated, clamps the rod to the boom and against longitudinal movement. The clamp guide provides a pivot means to permit pivotal movement of the rod relative to the boom and is spaced varying distances from the pivot 27, as is explained more fully hereinafter.

Referring particularly to FIGS. 5, 6, the guide clamp 31 includes a base member 32 which has a circular recess into which is tightly received the outer race 83 of a ball bearing 84 bolted in a recess in a slide member 85 by a co-axially located bolt 86. The head and nut of bolt 86 are recessed beneath the outer surfaces of the base member 82 and the slide 85, and a bearing 87 is interposed between the head and the base member so that the base plate may rotate freely about the axis of the hearing.

A clamp block 88 is bolted to the outer surface of the iember 82 and has a semi-cylindrical recess 89 across a side face thereof, as shown, the walls of which recess partially embrace rod 80. A second complementary clamp block 99, having a semi-cylindrical recess 91 in the side facing block 88, is attached to a piston 92 which is positioned in a hydraulic motor type cylinder 93 bolted to h the member 82. The walls of recess 91 cooperate with the walls of groove 89 to engage and clamp the rod 80 therebetween when fluid pressure is applied to the interior of the cylinder 93 through a flexible hydraulic line 94 connected to the cylinder by a T-coupling 95. When the fluid pressure is reduced in the cylinder 93, the block moves from the block 88 by the force of a spring 96 to release the rod 80. The grooves 89, 91 are located so that the centerline of rod 86 guided and supported by these grooves intersects the extension of the axis of bearing 84. It will be seen that the clamp 81 rotates about the center of bearing 83 to permit longitudinal sliding of rod 80 relative to the boom 22 and to permit relative rotation of the boom and rod during certain movements of the boom and dipper stick.

Assuming a parallelogram having as its corners the pivot 27, the center of bearing 84, the pivots 62 and 75, should the dipper stick swing about the pivot 27, the side of the parallelogram corresponding to the link 61 would remain at a given angle to horizontal, provided the position of pivot 27 remained fixed relative to horizontal, and would rotate relative to the long side of the parallelogram corresponding to the dipper stick between pivots 27 and 62. The present invention provides means to automatically operate motor 32 to shift the link 61, as well as the bucket 24 about its pivot 31, in substantial correspondence to the angular shift between the line through the centers of the pivot 27 and the bearing 84 and a line through the centers of pivots 27 and 62 which occurs during a swinging movement of the dipper stick relative to the boom. Thus, the angle of the side 35 of the bucket relative to the ground will remain substantially constant when the conditions mentioned prevail. This control of the motor 32 is effected by the valve 66 when the rod 80 is clamped to the boom 22 by the clamp guide 81 so as to form, in elfect, a long side of the parallelogram described. When the rod 80 is clamped to the boom, any tendency of the linkage comprising link 74, valve 66 and rod 80 to either elongate or contract actuates the valve to operate the motor 32 to move its piston in one direction or the other and cause the linkage to remain at the length established by clamping the rod 80 to the boom. More specifically, the valve 66 will be operated and cause the piston 63 to maintain the parallelogram described and thereby maintain the angle of the bucket to a given grade. When the rod 80 is permitted to slide in the guide 81, no parallelogram action is established and therefore there will be no automatic control of the bucket. A more complete description of the control of the motor 32 is set forth hereinafter.

It will be appreciated that when the bucket 24 is to grade along a fiat plane, such as shown at L, when the centerline of the dipper stick, which is a line through the pivots 27 and 31, is normal to the grade to be cut, the boom will be at its highest elevation. To position the dipper stick to initiate a scoop action the dipper stick is swung at an obtuse angle to the boom and the boom is lowered somewhat to position the bucket at the proper grade level as seen in full lines in FIG. 1. Then as the dipper stick is swung through a scooping or crowding movement, the boom is raised to maintain the grade level and after the dipper stick passes through its normal position relative to the grade level, the boom is lowered again to maintain the bucket on the level of the grade. It will be appreciated that during the bucket action described, the movement of the boom towards its highest elevation will tend to rotate the bucket to a more open position, i.e. to rotate the bucket towards an unloading position. As the boom is lowered to maintain the proper bucket level after the dipper stick has passed its normal position relative to the grade, the lowering movement of the boom tends to tilt the bucket towards a more closed position in which the open side 33 will tend to face upwardly. To compensate for this tilting imparted to the bucket by the movement of the boom, means is provided for shifting the position of the center of the bearing 84 along the boom as the boom shifts relative to the dipper stick so that the valve 66 is operated to cause the motor 32 to position the bucket more towards the open position during the beginning and ending of the full strokes of the dipper stick to compensate for the bucket closing effect of the boom movements. This means comprises a T-shaped track 100 attached to the boom along the centerline through the pivot 27 and the flanges of which track are received in an undercut groove 101 formed in the under side of the slide 85. An L-shape bracket 102 is secured to one end of the base member 82 and block 88 and has a bearing 103 attached thereto in axial align ment with the center of bearing 84. A link 104 is pivotally attached to the bearing 103 and the opposite end is secured to a pin 105 which may be positioned in one of a series of openings in a plate 106 attached to the dipper ,stick parallel to the centerline thereof. As the dipper stick swings from a right angle position relative to the boom to a relatively obtuse angle with the boom, the link 104 will slide the guide clamp 81 nearer to the pivot 27 and tend to effectively shorten the length of the rod 80' between the clamp and the operating spool 76 of the valve 66, thereby automatically compensating valve 66 to control the position of the piston 63 so as to rotate the bucket to a more open position, i.e. increase the angle between the centerline of the dipper stick and the plane of the open side 33 of the bucket, than would be the case if the clamp guide remained fixed relative to pivot 27.

As the dipper stick travels towards an acute angle with the boom, the link 104 moves the clamp guide 81 out- 6 wardly of the boom causing an effective shortening of the control link so that the valve 66 is operated to control the piston 63 to move the bucket towards a more open position to compensate for the tendency of the boom to close the bucket.

It will be appreciated that the linkage 104 shown is not necessarily to scale and that different dimensioned booms and dipper sticks will require different length and relative positions. It is desirable to provide adjustment for the position of the anchored end of link 104 and this may be provided by arranging for spaced openings 107 in the plate 106.

Refer-ring to FIG. 7, the hydraulic control circuit for the bucket; control motor 32 and the clamp 81 is shown schematically and it comprises a conventional hydraulic power system including a fluid pump 110, which withdraws oil from a reservoir tank 111 and discharges it under pressure through a suitable line 112 to a manually controlled diverter valve 113, located convenient to the operator and which is operative to alternatively direct the the oil fed thereto through a line 114 to a manually operated control valve 115 or through the line 94 to the cylinder 93 of the clamp 81. The control valve 115, which is conveniently located for the operator of the shovel, has lines 117, which communicate with opposite ends of the cylinder 64 of the motor 32 by which the piston rod 63 can be driven in opposite direction or to be locked in any given position according to positioning of the valve. The control valve 115 returns exhaust oil to the tank 111 through a line 121 and oil from the diverter valve 113 flows through the valve 115 and returns to the tank 111 when the valve 113 diverts oil from the control valve 115.

The inlet port of valve 66 is connected by a line 123 to the T connection 95 and receives oil under pressure from the diverter valve 113 by way of line 94. The valve 66 is operative when the spool 76 thereof is moved inwardly from a neutral position to direct oil into the upper end of the cylinder 64 through a line 124 connected into line 117, and to exhaust oil from the lower end of the cylinder through lines 120, 125, exhaust port 126 of valve 50, return line 127 to line 124. When the spool 76 is moved outwardly from its neutral position, fluid is directed into the lower end of the cylinder 64 and exhausted from the upper end, in the manner apparent from the preceding description.

The valves 66, 113, 115 are of well known construction and are readily available commercially and therefore the details thereof are not described. Furthermore, since the valves and system for operating the motors 14 and 21 .are well known, they are not shown or described. For sake of clarity certain of the hydraulic lines have been omitted or broken away in the drawings.

Referring more specifically to the bucket positioning means 52, the bucket is supported on the rocker shaft 51' so that it can be rotated about an axis extending in the plane in which the dipper stick swings. Referring more particularly to FIGS. 9 through 12, the positioning means comprises a rigid metal housing 130 comprising a closed ended trough-like portion 131 which has a top wall 132 bolted thereto. The top wall 132 has the pairs of lugs 54, 55 attached thereto which are attached to the dipper stick 23 and link 57, as mentioned previously. The rocker shaft 51 is rotatably supported in suitable bearing in the end walls 133, 134 of the housing 130 and has end portions projecting from opposite ends of the housing and which are rigidly attached to the U-shaped bracket 50 to which the bucket 24 is attached.

The rocker shaft 51 is adapted to be rotated to position the bucket so that its leading edge 33 thereof can be tilted about an axis lying in the plane in which the dipper stick swings, as seen in broken lines in FIG. 10. The portion 135 of the rocket shaft 51 intermediate the ends 133, 134 of the housing 130 is of substantially larger diameter than the end portions thereof and has a plurality of splines 136 which project from the surface thereof 7 and which are in the form of a spiral. A sleeve 137 surrounds the portion 135 of the rocker shaft 51 and has internal grooves which receive the splines 136 so that by moving the sleeve longitudinally of the rocker shaft the cooperation of the splines in the grooves of the sleeve impart rotation of the rocker shaft.

The sleeve 137 is adapted to be moved longitudinally of the rocker shaft and to be retained from rotary movement relative thereto by oppositely outwardly extending flanges 140, 141, the lower edges of each ride on slideways 142, 143 respectively, formed on the side and bottom walls of the housing and extending longitudinally thereof. The upper edges of flanges 140, 141 have gear racks 144, 145 therealong on which gear wheels 146, 147 mesh. The gear wheels are journaled on pins 150, 151 secured in a U- shaped member 152, the closed end portions of which has sliding surfaces 153, 154 which engage the top wall 132 and the adjoining side wall of the housing 130 and are guided therealong.

A cylinder 155 is welded to the member 152 and has axial openings in opposite ends through which a hollow piston rod 156 extends and which piston rod carries a piston 157 attached thereto closely fitting within the walls of the cylinder. The piston rod 156 is fixed at opposite ends in openings through the end walls 133, 134 of the housing, and suitable flexible hydraulic lines, not shown, are coupled therewith by which hydraulic fluid from a hydraulic system on the shovel can be introduced and discharged from opposite ends of the piston rod by a suitable valve under control of the operator. Openings 160, 161 are formed in the piston rod 156 adjacent opposite sides of the piston 157 so that fluid can be introduced into the cylinder 155 on opposite sides of the piston through opposite ends of the piston rod. It will be seen that by forcing fluid into one end of the rod 156 the cylinder 155 will be driven towards that end of the piston rod in which the fluid pressure is admitted, and the oil on the opposite side of the piston will move outwardly through the opposite side and end of the piston rod. It will be understood that the piston rod is closed between the portions having the openings 160, 161.

Two rack gears 162, 163 are formed on the insides of the housing side wall and top Wall and extend parallel to the gear racks 144, 145 and are engaged by the gears 146, 147, respectively. It will be seen that the shifting of cylinder 155 and the attached member 152 along the piston rod 156 causes the gears 146, 147 to drive the sleeve 137 through twice the distance of the movement of the cylinder and thereby rock the shaft 51 and rotate the bucket 24 about its axis.

The hydraulic fluid system for operating the cylinder is not shown inasmuch as such systems and control valves therefor are well known in the art.

It will be seen that the bucket positioning structure 52 provides means by which the angle of the bucket can be shifted to cause the leading edge 34 of the bucket to travel on a line or in a plane sloping relative to horizontal. For example, if it is desired to scoop dirt to form a ditch having a sloping side, the shovel may be positioned so that the boom and dipper stick swing in a plane extending longitudinally of the ditch and by rotating the bucket through the mechanism 52 the bucket will cut the earth on the desired slope. By providing the automatic control for moving the cutting edge of the bucket in a given plane to retain the leading edge at a constant angle with a given level, a ditch having a desired sloping wall can be readily formed.

In operation, when it is desired to cause the bucket or scoop 24 to remain at a substantially given angle relative to a grade to be cut which is indicated at L in FIG. 1, the operator manually controls the motor 32 to position the bucket at the desired angle relative to the dipper stick so that the most eflicient scooping angle will be formed relative to the grade which is to be formed and with the dipper stick normal to the grade. The diverter valve 113 is then operated to divert fluid from manual control valve 115 into line 94 which then locks rod to the clamp guide 81 and admits power fluid to valve 66. The operating plunger 76 of the valve 66 is normally strongly biased in a neutral position and when the rod 80 is clamped .to the boom, it will be seen that any relative movement of the link 61 and the line through pivot 27 and the center of bearing 84 will operate the valve through the link 74 and rod 80.

As the dipper stick is operated to its extended position and then drawn toward the platform in a scooping movement, the bucket will tend to rotate about its pivot 31 and move the links 61, 74 towards valve 66. Since rod 80 is clamped to the boom, the swinging movement of the end portion of the boom beyond the pivot 27 draws the spool 76 upwardly relative to the housing of the valve 66 which operates the valve to the piston 63 to be drawn into the cylinder 64 and move the bucket and links 61, 74 upwardly thereby moving the valve housing upwardly to tend to restore the spool to its neutral position with respect to the valve. It will be apparent that any relative movement of the housing of valve 66 and its spool 76 from neutral position results in operation of the motor 32 which tends to restore the valve to the neutral position by appropriate action of the piston 63. Thus, the motor piston 63 will follow the valve during the swinging movement of the dipper stick and boom and thereby properly position the bucket about its pivot 31 as the boom and dipper stick are moved through a grade stroke. As mentioned previously, the tendency of the raising boom to open the bucket relative to the level L is oilset by the shift in position of the clamp guide 81 along the boom as is the tendency of the lowering of the boom to close the bucket during the latter portion of the scooping movement.

When the diverter valve 113 is moved by the operator to restore control of the motor 32 to the control valve 115, the clamp guide 81 is released by the diversion of fluid from line 94 and the rod 80 then slides relative to the boom and the spool 76 of valve 66 remains in neutral position during operation of the motor 32 by the control valve 115.

Referring to FIGS. 14 and 15, a fragment of a power shovel 200, which is similar to the shovel 20, is shown which comprises the distal end of a dipper stick 201 having a scoop or bucket 202 pivotally carried thereon by a pivot pin 203. The bucket 202 is generally like the bucket 24 and is moved about the pivot 203 by a hydraulic motor 204 having a piston 205 connected to a link 206 which is pivotally connected to the dipper stick 201 at 207. It is immaterial to the present form of the invention as to the manner in which motor 204 is controlled, but preferably it may be controlled automatically as described with reference to motor 32 to cause the bucket 202 to remain in a given angle relative to a grade being cut by the bucket. In accordance with the form of the invention shown, the bucket 202 may be rotated about an axis lying in the plane in which the dipper stick swings so that the leading edge of the bucket can be tilted from horizontal for grading sloping sides of ditches and the like by swinging the boom and dipper stick in a vertical plane.

The construction of the bucket 202 may be similar to that as described with reference to bucket 24, including two parallel support flanges 210, 211 which have openings receiving support pins 212, 213. The pins 212, 213 are supported in two pairs of lugs 215, 216 which are attached to the bottom side of a bracket 217.

The bracket 217 is adapted to swing about the pin 203 on an axis extending normal to the plane in which the boom and dipper stick swing and also about a shaft 220 on an axis lying in the aforementioned plane. In the form of the invention shown, this pivotal support is effected by a bushing 221 in which the shank 220 is journaled and which bushing has a U-shape bracket 222 at- 9 tached thereto, the outer ends of which bracket is supported by the pin 203. The ends of the shank 220 are attached in openings in an upturned end portion of the bracket 217 and a lug 218 attached to the bracket and extending parallel to the upturned end, as seen in FIG. 14.

The right hand end of the bracket 217 has an upstanding web plate 219 welded thereto having rods 223 projecting from opposite sides of the bracket and in axial alignment with one another. The rods 223 are welded to the outer race 240 of a ball bearing 224 which is in turn welded to the web 219 so that the axis of rotation thereof is aligned with the axis of shaft 220. Thus, the rods 223 are integral with the bracket 217 and may be tilted by power means described hereinafter, to position the bracket 217 and the bucket 202 attachedthereto about the axis of the shaft 220 and the bearing 224.

The bracket 217 and the bucket 202 supported thereby are tilted and positioned about the pivot 203 by a link 225, pivotally attached at its upper end to the link 206 and the outer end of the piston 205 by a pin 227. The lower end of the link 225 is pivotally attached at 244 to a cross rod 243 welded to the inner race 241 of the bearing 224 so that the centerline of the rods 223 extend through the center of the connection 244.

The rods 223 are moved to tilt the bucket 202 about the axis of the shaft 220 by two single acting hydraulic piston type motors 230, 231 having the upper ends of the cylinders thereof attached to the pin 227 by universal joints 232, 233 and the pistons 234, 235 are attached to the outer ends of the rods 223 by universal joints 236, 237. The pistons 234, 235 are driven from the cylinders by hydraulic fluid directed to and from the cylinders by conventional hydraulic control valve and fluid pressure supply means which are not shown as such means are well known. Thus, by controlling the motors 230, 231 the position of the bucket 202 can be altered about the axis of the shaft 220 which lies in the plane in which the dipper stick swings and one of which positions is indicated by broken lines in FIG. 15.

The universal joints 232, 233, 236 and 237 permit the racket 217 and bucket 202 to be rotated about the pivot 203 as well as about the axis of shaft 220.

It will be seen that by my invention the angle of the bucket about an axis normal to the plane in which the boom and dipper stick swing can be maintained substantially constant during an earth scooping action so that a level grade may be easily formed. The operator may readily control the shovel so that he can select either manual or automatic control of the bucket about the axis mentioned.

The invention also provides means whereby the operator can adjust the position of the scoop bucket about an axis extending in the plane in which the boom and dipper stick swing so that the leading edge of the bucket during a scooping action cuts the earth on a slope. It will be seen that this construction permits the shovel to form a side of a ditch, for example, by merely swinging the boom and dipper stick longitudinally of the ditch, thereby facilitating excavations of this type.

Although I have described but two forms of the invention, it will be understood that other forms, modifications and adaptations could be made all falling within the scope of the claims which follow.

I claim:

1. A power shovel comprising a boom, a dipper stick pivoted to said boom, a bucket, pivot means pivotally attaching said bucket to said dipper stick for movement of said bucket about an axis normal to the plane in which said dipper stick swings, means for shifting said bucket about said pivot axis in response to a change in the angle between said dipper stick and said boom and comprising a motor for moving said bucket about said pivot means, and control means for said motor operative in response to a change in angle between said dipper stick and said boom.

2. A power shovel as set forth in claim 1 including means to selectively render said control means operative and inoperative. 3. A power shovel as set forth in claim 1 including a manual control for said motor, and means to alternatively render said control means operative and said manual control inoperative and vice versa.

4. A power shovel as set forth in claim 1 in which said control means includes a movable control member normally in a neutral position and movable to two alternative control positions, means supporting said member for relative movement with respect to said boom, and means to selectively lock said member to said boom.

5. A power shovel as set forth in claim 1 in which said motor comprises a hydraulic cylinder and piston, means supplying hydraulic fluid under pressure to said motor, and said control means comprises a valve for controlling the flow of hydraulic fluid to and from said cylinder, and means to control said valve comprising link means connected to said valve and to said boom for operating said valve in response to changes in angle between said dipper stick and boom.

6. A power shovel as set forth in claim 5 including means for selectively locking said member to said boom for movement therewith.

7. A power shovel as set forth in claim 6 in which said means for selectively locking said member to said boom comprises hydraulic means responsive to hydraulic fluid directed to said control valve.

8. A power shovel as set forth in claim 7 in which said hydraulic means includes a valve operative to selectively direct hydraulic fluid to or divert hydraulic fluid from said control valve.

9. A power shovel as defined in claim 1 in which said motor comprises a hydraulic cylinder supported on said dipper stick and piston means therein connected with said bucket, a hydraulic valve, means supporting said valve on said dipper stick, said valve having a housing and a valve operating member movable relative to said valve housing, link means interconnecting said housing and said bucket for shifting said housing in response to changes in the angle between said dipper stick and said bucket, second link means interconnecting said operating member with said boom, said second link means including a link rod and guide means on said boom to guide said rod relative to said boom, said guide means including means to selectively lock said rod to said boom.

10. A power shovel as defined in claim 9 including means to shift said guide means along said boom in response to changes in angular position of said boom relative to said dipper stick.

11. A power shovel comprising a boom, a dipper stick pivotally supported by said boom for swinging in a vertical plane, a bucket, and means attaching said bucket to said dipper stick for pivoting about an axis extending in said vertical plane whereby the lower portion of said bucket can be swung from one side to the other of the plane in which said dipper stick moves, said means comprising a housing, means attaching said housing to said dipper stick, a shaft journaled in said housing and extending from opposite ends, bracket means on said bucket attached to opposite ends of said shaft, and hydraulic drive means in said housing for rotating said shaft.

12. A power shovel as defined in claim 11 in which said hydraulic drive means comprises a helical formation on said shaft, a sleeve threaded on said formation, a cylinder attached to said sleeve, a piston rod rigidly fixed in said housing, a piston in said cylinder and attached to said rod, and means for admitting and exhausting fluid from said cylinder on opposite sides of said piston for driving said cylinder along said piston.

13. A power shovel as defined in claim 11 in which said means comprises a two-part frame, means pivoting a first part of said frame to said dipper stick for rotation about an axis extending normal to said vertical plane, bearing means pivotally connecting said two parts of said frame together on an axis extending in said vertical plane, said bucket being attached to said second part of said frame, extendable and retractable power means, means supporting one end of said power means on said dipper stick, and means attaching the other end of said power means to said second frame part at a point laterally of said axial connection between said parts of said frame, whereby said power means is effective to rotate said second part of said frame and said bucket about said pivotal connection between said parts of said frame.

14. A power shovel as defined in claim 13 further characterized by said power means comprising a pair of hydraulic cylinder and piston type motors disposed on opposite sides of a plane through the center of said dipper stick and extending in the direction of pivotal movement of said dipper stick, said motors being connected to said second part of said frame at points laterally of the last mentioned plane and on opposite sides thereof, universal joints between said motors and said dipper stick, and uni- 12 versal joints between said motors and said second frame part.

15. A power shovel as defined in claim 14 further characterized by a rigid link interconnecting said dipper stick and said first part of said frame, and means for moving said link longitudinally to swing said frame and said bucket about said axis extending normal to the plane in which said dipper stick swings, said link and said power means lying within a substantially common plane.

References Cited UNITED STATES PATENTS 1,682,774 9/1928 Clutter 214138 1,693,809 12/1928 7 Clutter 214138 3,033,394 5/1962 Kashergen 214-138 3,034,671 5/1962 Schwellenbach 214138 3,231,116 1/1966 Powell 214-138 HUGO O. SCHULZ, Primary Examiner. 

1. A POWER SHOVEL COMPRISING A BOOM, A DIPPER STICK PIVOTED TO SAID BOOM, A BUCKET, PIVOT MEANS PIVOTALLY ATTACHING SAID BUCKET TO SAID DIPPER STICK FOR MOVEMENT OF SAID BUCKET ABOUT AN AXIS NORMAL TO THE PLANE IN WHICH SAID DIPPER STICK SWINGS, MEANS FOR SHIFTING SAID BUCKET ABOUT SAID PIVOT AXIS IN RESPONSE TO A CHANGE IN THE ANGLE BETWEEN SAID DIPPER STICK AND SAID BOOM AND COMPRISING A MOTOR FOR MOVING SAID BUCKET ABOUT SAID PIVOT MEANS, AND CONTROL MEANS FOR SAID MOTOR OPERATIVE IN RESPONSE TO A CHANGE IN ANGLE BETWEEN SAID DIPPER STICK AND SAID BOOM. 